The Lincoln Calibration Sphere 1, or LCS-1, is a large aluminium sphere in Earth orbit since 6 May 1965. It is still in use, having lasted for over 50 years.
[ The sphere was launched along with the Lincoln Experimental Satellite-2 on a Titan IIIA. It is technically the oldest operational spacecraft , but it has no power supply or fuel; it is merely a passive metal sphere. LCS-1 has been used for ]radar calibration
Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, we ...
since its launch. It was built by Rohr. Corp. for the MIT Lincoln Laboratory.[ The sphere was constructed from two hemispheres, made by spinning sheet metal over a mold. These hemispheres were fastened to an internal, circumferential hoop by 440 countersunk screws, then milled and polished. The initial finish had a ]surface roughness
Surface roughness, often shortened to roughness, is a component of surface finish (surface texture). It is quantified by the deviations in the direction of the normal vector of a real surface from its ideal form. If these deviations are large, ...
less than 10 micrometres and was expected to last for five years.optical cross section
Optical cross section (OCS) is a value which describes the maximum amount of radiant flux, optical flux reflected back to the source. The standard unit of measurement is m2/sr. OCS is dependent on the geometry and the reflectivity at a particula ...
of the LCS-1 was measured in L, S, C, X and K microwave bands. Four other spheres were also manufactured and measured for comparison to the one in orbit.
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Satellites of the United States
Satellites orbiting Earth
Passive satellites
Spacecraft launched in 1965
Radar calibration satellites
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